Pomacea insularum

Island Apple Snail, Pomacea insularum (d'Orbigny 1837).

The Island Apple Snail is an invader from South America. It is a growing pest, infesting freshwater ponds and waterways across much of Texas, Georgia, and Florida. If you explore the bayous, drainage ditches, and retention ponds in the Houston area, you are almost sure to find this snail. Look for empty shells and pink egg clusters by the waterline. You may examine them as much as you want, but do NOT take them home- it is illegal to possess or transport Apple Snails in the state of Texas. If you find Apple Snails in your area, you are encouraged to notify Texas Parks and Wildlife.

The shell of the Apple Snail is green or purplish-brown, often striped, and can grow to be the size of a baseball. The body is lighter in color, usually gray with yellow accents, and is mottled with dark, freckle-like markings. Like most aquatic mollusks, the eyes are located on the body itself, not on eyestalks. It also boasts two pairs of tentacles and a tubular siphon, which are sensory tools. The siphon allows the snail to inhale oxygen from the surface while remaining submerged. A thick operculum protects the snail while in its shell, and rests on the dorsal side and posterior end of the mantle when the snail is out. When frightened, the snail pulls itself into the shell, causing the mantle to fold in half like a piece of paper. The operculum then seals the aperture.

Every 12 to 15 days, female Island Apple Snails lay bright pink egg clusters on reeds, plants, and other objects above the water's surface. These clusters resemble blobs of roseate styrofoam, and generally contain up to 500 individual eggs. Juvenile snails hatch after 10 to 15 days, and reach maturity by 2 to 3 months. Because each female Apple Snail produces up to 15,000 offspring every year, the population grows exponentially. Apple Snails have voracious appetites for aquatic plant matter, and can out-eat native species competing for food. As a result, these native species are threatened with extinction. The only way to save them is to eliminate the Island Apple Snail from our waters.

Unfortunately, this snail is extremely tough. Even though it is an aquatic animal, it can survive for weeks out of the water. The thick shell holds moisture well, and is strong enough to withstand a lot of damage. They can tolerate near-freezing weather and temperatures over 100 degrees Fahrenheit. They are also highly resistant to toxins. A good hit with a hammer will destroy the shell, but it leaves shards lying around that are razor-sharp. If you are a collector, boiling or freezing the snails may be the only way to kill them without damaging the shell.